I tried kill -9 698 but the process did not die.
kill -9 698
$ ps -ef | grep chromium 502 698 811 0 0:01.24 ?? 0:07.28 /Users/lucius/chromium/
I recently faced similar issue where the atom editor will not close. Neither was responding. Kill / kill -9 / force exit from Activity Monitor - didn't work. Finally had to restart my mac to close the app.